[jpstewart]

and something on the right-most expansion slots with a row of BNC connectors (I presume this is something to do with analog video as one of the connectors has a 75Ohm terminator plugged in). I did not have a closer look on that board, I only noticed it now reviewing my photos. What is this card with the BNC connectors

That appears to be the Octane Digital Video (DIVO) option board.

and/or the one below it (which has something that looks like two 9-pin D-connectors with one hole plugged for some reason)?

That's an old-school fibre channel board using copper cabling. 1Gbit/sec, first generation fibre channel, and not really interoperable with fibre channel that uses fibre optic cabling. They were used for connecting directly to fibre channel storage.